1. Field of the Invention
The invention relates to a rotary shaker which includes two pairs of flexible straps, mounted at right angles with respect to each other, that constrain the motion of the shaker tray to a circular, controlled orbit which results in a smooth action with minimal power input.
2. Description of Related Art
The prior art literature describes a limited number of efforts to support a variety of different shaker mechanisms with flexible members. The following is believed to be a relevant sampling of that prior art.
U.S. Pat. No. 4,183,677 issued Jan. 15, 1980 and entitled "MECHANISM FOR EFFECTING ORBITAL MOTION OF A MEMBER" describes a shaker device which includes four resilient flexible springs which collectively form the four corners of a square. The flexible springs provide support and control for the orbital motion of the shaker. The mechanism, however, appears to be moderately complicated. Note also, U.S. Pat. No. 4,147,516, issued to Norman A. DeBruyne, the inventor named in U.S. Pat. No. 4,183,677. That patent describes another oscillating mechanism including the use of flexible, vertical members for supporting a platform.
U.S. Pat. No. 5,427,451 entitled "MIXER WITH AN OSCILLATING DRIVE" describes a laboratory device which includes a set of leaf springs which support and control the oscillatory motion of the device. The structure of that device, however, appears to be adapted primarily for use with ultrasonic drivers and, accordingly, does not appear to be appropriate for mixers of a different speed range.
U.S. Pat. No. 5,060,150 issued on Oct. 22, 1991 and entitled "SPEED CONTROL FOR ORBITAL SHAKER WITH REVERSING MODE" discloses another laboratory shaker which includes flexible, vertical elements for supporting an upper platform by a lower platform.
U.S. Pat. No. 3,539,156 issued on Nov. 10, 1970 and entitled "VIBRATOR 0R SHAKER" describes another laboratory device in which a pedestal includes a support means that is resiliently suspended by the pedestal.
U.S. Pat. No. 639,404 entitled "MACHINE FOR SHAKING BABCOCK MILK TEST BOTTLES" and issued on Dec. 19, 1899 describes an industrial mixer including two supports which act like springs which permit the upper section of the mixer to oscillate back and forth with respect to the rest of the support mechanism.
U.S. Pat. No. 5,060,151 issued on Oct. 22, 1991 and entitled "SPEED CONTROL FOR ORBITAL SHAKER WITH REVERSING MODE" discloses a unique suspension mechanism including a pair of flexible links which permit a support tray to oscillate between two different positions.
U.S. Pat. No. 4,422,768 issued on Dec. 27, 1983, entitled "PAINT CAN SHAKER" describes another shaker mechanism including a plurality of flexible support springs.
U.S. Pat. No. 5,052,812 issued on Oct. 1, 1991 and entitled "BATH SHAKER" and U.S. Pat. No. 5,372,425 issued on Dec. 13, 1994 and entitled "CUSHIONED RESTRAINING DEVICE" are examples of conventional shakers of recent design but having substantially different suspension mechanisms. Both U.S. Pat. Nos. 5,052,812 and 5,372,425 are assigned to New Brunswick Scientific Company, Inc., the assignee of the present invention.
Lastly, U.S. Pat. Nos. 5,015,366; 4,176,750 and RE 31,660 are cited as being of general interest only but otherwise do not appear to be relevant to the present invention.
None of the foregoing prior art appears to teach or suggest a simple, low-cost, effective rotary shaker apparatus employing resilient members in a structure such as that described in this disclosure and, moreover, none of the prior art devices appear to describe or suggest the unique manner in which the flexible resilient members are attached to the rigid portion of the supporting frame.